Concern vs. worry
There's no way to avoid being concerned about your grandson's welfare, but worry and concern are two different things.
Worry comes from "magical thinking"--"if i just worry hard enough, maybe i can keep him safe." well you can't. He's either safe or he's not. So be concerned and try to find out how he's doing, but please don't worry, because it only makes you a wreck. Hoping for good news.